Spark-plug.



No. 795,460. PATENTED JULY 25, 1905. F. A. THURSTON.

SPARK PLUG.

APPLICATION FILED JUNE 27. 1904.

i Z- fy 1 10 2'0 l'i ,7 v :1 65-0 I l J 1 u i5 J J'J 1K engine-cylinder 1.

FREDUS A. THURSTON, OF CHICAGO, ILLINOIS.

SPARK-PLUG- Specification of Letters Patent.

Patented July 25, 1905.

Application filed June 27, 1904:. Serial No. 214,387.

To all whom, it may concern.-

Be it known that I, FREDUS A. THURSTON, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Spark-Plugs, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification,

My invention relates to spark-plugs, and in particular to a form thereof especially adapted for use in gasolene and like engines.

Prominent objects of the invention are to provide asimple, practical, and inexpensive form of plug, to secure an effective and efficient action thereof in creating sparks, and to make it practically impossible for the plug or its parts to become injured or to become inoperative or ineffective by reason of the op eration of the plug or the continual rough usage which it receives when in use upon en'- gines in automobiles, launches, and the like.

In the accompanying drawings, Figure 1 is a longitudinal section of a spark-plug embodying my invention and a portion of the cylinder of a gasolene-engine. Fig. 2 is abottom view of the same. Fig. 3 is a cross-section taken on line 3 3 in Fig. 1. Figs. 4 and 5 are views of details of construction.

Referring first to Fig. 1, a portion of the engine-cylinder is shown at 1, and the sparkplug 2 is shownfitted into said cylinder. This plug is conveniently made in the form of a cylindric tubular shell or casing having its lower end screw threaded, so as to fit into the The upper end of said casing is interiorly threaded, as at 3, and receives a threaded nut 4. Below the nut 4 are washers 5 and 6, which also fit into the threaded socket 3. An electromagnet 7 is secured to the washer 6 and depends therefrom, so as to lie within the shell 2. Below the lower end of the magnet is a disk 8, of mica, and below this is a metal wall or partition 9, which extends across the shell 2 and closes the same below the magnet 7. As a convenient arrangement the outer edge of the metal partition 9 is bent up so as to form a cup-shaped structure, as shown in Fig. 4, and this is fitted tightly into the shell 2. The interior of the shell between the washer 6 and the partition 9 is desirably filled with cement 10, by which the magnet 7 is secured firmly in place and is insulated and protected. Below the partition 9 is the armature 11 of the magnet,

and this armature is pivoted at 12 to one side of the metal shell 2 and held in a normally retracted or lowered position by a leaf-spring 13. An arm 14 is extended out from the other side of the shell 2, so that its inner end lies below the inner end of the armature 11. This arm 14 is provided with a contact 15, adapted to make electrical connection with the armature 11. The arm 14 is insulated from the shell 2 and is supported thereby. The magnet 7 is connected by an insulated conductor 17 with one side of the circuit, and the other end of the magnet is connected by a conductor 18 with the arm 14, and this by contact with the armature 11 afiords connection with the metallic casing or shell 2, which is connected, by means of the enginecylinder, with the other side of the circuit.

When the magnet is energized, it attracts the armature 11, thereby breaking connection between that armature and the arm 14, so that at once the circuit is broken and the magnet 7 becomes denergized. This permits the armature 11 to drop, thereby again closing the circuit and causing the magnet 7 to again become energized. This attracts the armature 11 and again opens the circuit. In this way a continual vibration of the armature 11 is caused to take place as long as the circuit is closed through the magnet 7, this vibration of the armature 11 causing a continual make and break and produces sparks which ignite the gas in the enginecylinder.

It will be seen that by the partition formed by the disk 8 and wall 9 the magnet 7 is completely inclosed and is thereby protected against injury of all kinds and is thoroughly insulated by the cement 10 and is maintained in a cool condition. In this way the structure of the spark-plug is preserved from all damage and injury such as might be caused by heat and explosions of the engine, and the life of the plug is thus indefinitely prolonged and its action maintained effective. As a matter of further improvement the interior of the shell 2 is desirably provided with annular recesses or grooves 20 20, which serve to hold the cement 10 firmly in position.

It will be understood that changes and modifications can be made in the device Without departing from the spirit of my invention.

What I claim is 1. A spark-plug comprising a shell or casing, an electromagnet confined therein, a composite Wall consisting of an insulating material and a layer of metal, and an armature combined With contacts arranged outside of said Wall, substantially as described.

2. A spark-plug comprising a shell or casing, an electromagnet confined therein, a mica disk at the end of said magnet, a metal partition outside of said mica disk, and an armature with contacts arranged outside of said partition, substantially as described.

3. In a sparkplug, the combination of an electromagnet, an insulating-disk arranged at the end thereof, a metallic structure alongside of said insulating-disk, and an armature on the side of said insulation and metallic structure opposite the magnet, substantially as described.

In Witness whereof I hereunto subscribe my name this 2d day of June, A. D. 1904. FREDUS A. THURSTON. Witnesses:

A. MILLER BELFIELD, I. 0. LEE. 

